In a standing mixer fitted with a dough hook combine the yeast and water, mixing slowly until yeast is dissolved. Stir in salt and sugar. Mix well. Set aside for 5 minutes.

Beat for 5 minutes, gradually adding flour until the dough begins to pull away from the sides of the bowl.

Turn out on a lightly floured surface. Knead for 8 to 10 minutes, until dough is smooth and elastic, adding flour as necessary to prevent stickiness.

Lightly oil a large bowl. Place dough in bowl and turn to coat on all sides. Cover with plastic wrap and let rise in a warm, draft-free place until doubled in bulk, about 1 1/2 hours. Alternatively, cover with plastic wrap and let rise slowly in the refrigerator for 10 to 12 hours or overnight.

Line a baking sheet with kitchen parchment or sprinkle with cornmeal.

Punch down the dough. Divide in half, shape into 2 round loaves, and place on the baking sheet. Carve an X in the top of the loaf and spray with vinegar. Place in a cold oven and turn the oven on to 400 degrees F for 45 minutes. Transfer to wire rack to cool.